An intensive effort was directed toward studying the preventive and therapeutic aspects of human immunodeficiency virus (HIV) infection and the acquired immunodeficiency syndrome (AIDS). A randomized trial comparing therapy with zidovudine (ZDV) versus interferon-alpha (IFN-alpha) versus the combination in 180 patients with early HIV-1 infection completed accrual and is currently active. A dose-tolerance study of the combination of IFN-alpha and dideoxyinosine completed accrual of 53 patients and is now gathering long-term follow-up data. A randomized, double-blinded, placebo-controlled Phase II study of L-697,661 versus ZDV completed accrual of 84 patients using surrogate markers as efficacy parameters and is now undergoing final analysis. A Phase I study of N-acetyl-cysteine was begun and has enrolled 23 patients to determine the pharmacokinetics, bioavailability, maximally tolerated dose, and preliminary efficacy of this agent in the treatment of HIV-infected persons with less than 500 CD4 cells/mm3. A phase I study of CD4-Pseudomonas Exotoxin (sCD4-PE40) in HIV-infected patients was initiated and enrolled 24 patients to determine the pharmacokinetics, maximally tolerated dose, and preliminary efficacy of this agent. Follow-up analysis of a randomized, controlled, masked trial of foscarnet in the treatment of cytomegalovirus retinitis in AIDS patients demonstrated an apparent survival benefit of this therapy.